3.3

• What is the motion of molecules in a gas?

  They are in constant random motion.
• What factor affects the average kinetic energy of gas molecules?

  The temperature of the substance affects the average kinetic energy.
• How does temperature relate to the average kinetic energy of gas molecules?

  The higher the temperature, the higher the average kinetic energy of the molecules.
• What effect does increasing temperature have on the pressure of a gas when held at constant volume?

  The pressure of the gas will increase as the temperature increases.
• Why does pressure increase as temperature increases at a constant volume?

  Kinetic energy of molecules increases, leading to more frequent collisions.
• What happens to the rate of collisions in gas A at low pressure compared to gas B at high pressure?

  There are more collisions per second in gas B than in gas A.
• Describe the force that the pressure of a gas exerts on the walls of its container.

  The net force acts at right angles to the container’s surface and increases as pressure increases.
• How does increasing the volume of a gas result in a decrease of pressure?

  Molecules become more spread out, increasing time between collisions and reducing the rate of collisions.
• What can be said about the product of pressure and volume for a fixed mass of gas at a constant temperature?

  The product of pressure and volume is constant.
• What is the unit used for pressure?

  Pascal (Pa)
• What increases when you do work on a gas?

  The internal energy of the gas increases.
• Why does the temperature of air inside a bike pump increase when it is pumped?

  Work is done on a gas when it is compressed, increasing its internal energy and average kinetic energy.
• What are the key points about the motion of gas molecules and their relationship with temperature and pressure?

  • Gas molecules are in constant random motion.
  • Average kinetic energy is affected by temperature.
  • Higher temperature leads to higher average kinetic energy.
  • Increasing temperature at constant volume increases pressure.
  • More collisions occur with increased temperature.
  • Low pressure gas has fewer collisions than high pressure gas.
  • Pressure acts at right angles to container walls.
  • Increasing volume decreases pressure due to spread-out molecules.
  • Product of pressure and volume is constant for a fixed mass at constant temperature.
  • Pressure is measured in Pascals (Pa).
  • Doing work on a gas increases its internal energy and temperature.